Portable radio communication devices are well-known. It is also well-known that there has been a long-continued trend toward micro-miniaturization of portable radio communication devices. This trend is especially important in devices that are designed to be worn on a user's body, such as a wrist-worn selective call receiver.
A problem that must be overcome is that micro-miniature housings required for micro-miniature radio communication devices leave little space for a required antenna. Wrist-worn receivers that attach to the user by a partially conductive wrist band and operate in a VHF radio frequency band near 150 MHz have typically used tiny ferrite core antennas in combination with the wrist band itself as a loop antenna. While this technique has performed well for the VHF band, it is not well suited for the much higher UHF and 900 MHz bands in use today and even higher frequencies planned for the future.
A further problem arises from a need to maximize antenna sensitivity while in a severe multipath fading environment. This problem is particularly acute in satellite-based systems, in which transmitter-to-receiver distance is large and transmitter power is limited. In addition, satellite-based systems utilizing low-Earth-orbit satellites (as opposed to geo-stationary satellites) exhibit a slowly changing multipath fading environment caused by earth reflection in conjunction with changing satellite azimuth as a result of orbital movement of the satellite.
Thus, what is needed is a micro-miniature antenna that performs well at UHF and higher frequencies. The antenna must be able to fit comfortably within a wrist watch-size housing. The shape of the antenna ideally will be able to conform to the geometry of the housing rather than forcing the housing to conform to a shape required by the antenna. Furthermore, the antenna must perform well in the slowly changing multipath fading environment present in low-Earth-orbit satellite-based systems.